Internet Speed Calculator
Evaluate whether your broadband tier meets your household needs. Translate ISP marketing numbers into real-world download minutes for games, movies, and updates.
Quick Calculation: Compare advertised ISP broadband plans with real-world download performance. At typical speeds, calculations account for TCP packet framing, Wi-Fi contention, and server delivery caps.
How Download Time Is Calculated
Real Speed = Advertised Speed × (1 - Protocol & Wi-Fi Overhead)Real-world speed accounts for TCP/IP headers, frame preamble, Wi-Fi channel contention, and signal degradation.
Convert to Bits
Multiply file size in Bytes by 8 to get total bits: 15 GB × 8,000,000,000 bits
Apply Speed & Overhead
Multiply network speed by real-world efficiency (typically 90% due to TCP/IP packet headers): 75 Mbps × 0.90
Divide to Find Duration
Divide total bits by effective throughput: 13 min 20 sec (theoretical) / 14 min 49 sec (with 90% real-world efficiency)
Internet Speed Calculator — Reference Table
Compare estimated durations for popular file sizes across common broadband bandwidths.
| File Size | 10 Mbps | 25 Mbps | 50 Mbps | 100 Mbps | 200 Mbps | 500 Mbps | 1 Gbps |
|---|---|---|---|---|---|---|---|
| 100 MB | 1 min 29 sec | 36 seconds | 18 seconds | 8.9 seconds | 4.4 seconds | 1.8 seconds | 889 ms |
| 500 MB | 7 min 24 sec | 2 min 58 sec | 1 min 29 sec | 44 seconds | 22 seconds | 8.9 seconds | 4.4 seconds |
| 1 GB | 14 min 49 sec | 5 min 56 sec | 2 min 58 sec | 1 min 29 sec | 44 seconds | 18 seconds | 8.9 seconds |
| 5 GB | 1 hr 14 min 4 sec | 29 min 38 sec | 14 min 49 sec | 7 min 24 sec | 3 min 42 sec | 1 min 29 sec | 44 seconds |
| 10 GB | 2 hrs 28 min 9 sec | 59 min 16 sec | 29 min 38 sec | 14 min 49 sec | 7 min 24 sec | 2 min 58 sec | 1 min 29 sec |
| 25 GB | 6 hrs 10 min 22 sec | 2 hrs 28 min 9 sec | 1 hr 14 min 4 sec | 37 min 2 sec | 18 min 31 sec | 7 min 24 sec | 3 min 42 sec |
| 50 GB | 12 hrs 20 min 44 sec | 4 hrs 56 min 18 sec | 2 hrs 28 min 9 sec | 1 hr 14 min 4 sec | 37 min 2 sec | 14 min 49 sec | 7 min 24 sec |
| 100 GB | 1 day 41 min | 9 hrs 52 min 36 sec | 4 hrs 56 min 18 sec | 2 hrs 28 min 9 sec | 1 hr 14 min 4 sec | 29 min 38 sec | 14 min 49 sec |
Frequently Asked Questions About Internet Speed Calculator
Why does my 100 Mbps plan download at 12 MB/s?
Because file downloads are measured in Megabytes (MB) and internet plans are sold in Megabits (Mb). 100 Mbps divided by 8 is 12.5 MB/s under ideal conditions.